Despite being diagnosed with Parkinsons, actor Michael J Fox continues to work as much as he can and maintains an inspirationally positive attitude.
Artist Frida Kahlo: in her childhood, she suffered from Heine-Medin disease, which resulted in a deformation of her leg. At the age of 18, she had a serious accident which required her to spent several months in a hospital, which is where she started painting. She miscarried two children, her second one being aborted around the time when her mother died. Her husband had an affair with her sister, Cristina, and another partner of hers, a Russian politician, was murdered in her residence. Later, her father died of a heart attack, and she'd undergone seven spine surgeries, which further led her into having to use a wheelchair. Despite her horrible life, shortly before her death, she created a painting which she titled "Viva la vida". Curiously, her earlier works were rather pessimistic.
Many saints are reported to be like this. They praise the goodness of God and die happily, even if they are going through incredibly painful diseases or ordeals. For example: St. Maria Goretti.
'"I keep my ideals, because in spite of everything I still believe that people are really good at heart."
This is Bob Ross's shtick. When he left the military, he vowed to never be "mean" again. He had hiccups in his life such as divorce, death and cancer but that didn't stop him from painting happy trees. In his own words: "I got a letter from somebody here a while back, and they said, 'Bob, everything in your world seems to be happy.' That's for sure. That's why I paint. It's because I can create the kind of world that I want, and I can make this world as happy as I want it. Shoot, if you want bad stuff, watch the news.".
Doug Walker is an eternal optimist, and shrugs off the numerous creepers, stalkers and hatefests he gets with a paraphrased "I could be starving or off fighting in a foreign country, problems coming from being an internet reviewer pale in comparison".